Selective production of arenes via direct lignin upgrading over a niobium-based catalyst

Lignin is the only large-volume renewable source of aromatic chemicals. Efficient depolymerization and deoxygenation of lignin while retaining the aromatic functionality are attractive but extremely challenging. Here we report the selective production of arenes via direct hydrodeoxygenation of organosolv lignin over a porous Ru/Nb₂O₅ catalyst that enabled the complete removal of the oxygen content from lignin. The conversion of birch lignin to monomer C₇-C₉ hydrocarbons is nearly quantitative based on its monomer content, with a total mass yield of 35.5 wt% and an exceptional arene selectivity of 71 wt%. Inelastic neutron scattering and DFT calculations confirm that the Nb₂O₅ support is catalytically unique compared with other traditional oxide supports, and the disassociation energy of C_aromatic-OH bonds in phenolics is significantly reduced upon adsorption on Nb₂O₅, resulting in its distinct selectivity to arenes. This one-pot process provides a promising approach for improved lignin valorization with general applicability.